TW202142655A - Adhesive sheet - Google Patents

Abstract

An adhesive sheet comprising a base material and an adhesive agent layer that is layered on one surface of the base material, wherein the base material is formed from a material comprising a polyester resin, and among the monomer units constituting the polyester resin, the molar ratio of monomer units having an aromatic cyclic structure with respect to monomer units having an alicyclic structure is at least 0 and less than 1. The adhesive sheet enables the suppression of manufacturing costs while also inhibiting the occurrence of chips from cutting.

Description

Adhesive sheet

The present invention relates to an adhesive sheet suitable for use as a workpiece processing sheet used in the processing of workpieces such as semiconductor wafers.

Semiconductor wafers, such as silicon and gallium arsenide, and various packages are manufactured in a large-diameter state. After the wafers are cut (dicing, also known as dicing), peeled (pickup, also known as pick-up), they are moved as a connection The steps of the installation (mount) step. At this time, the workpiece such as a semiconductor wafer is attached to an adhesive sheet (hereinafter, sometimes referred to as a "workpiece processing sheet") with a base material and an adhesive layer, and back grinding (back grinding) is performed , Cutting, cleaning, drying, expanding, crystal picking, mounting, etc.

As one of the above-mentioned cutting methods, there is a method of cutting a workpiece by a rotating disc knife (cutting blade). In this method, in order to surely cut the workpiece, usually the workpiece processing sheet attached to the workpiece is also partially cut together with the workpiece.

In this way, when the workpiece and the workpiece processing sheet are cut, cutting chips formed from the materials constituting the adhesive layer and the base material will generate the workpiece processing sheet. In particular, such cutting chips usually occur in the vicinity of the path (saw path, kerf line) through which the disc cutter passes in the wafer or workpiece processing sheet obtained by cutting.

When the chip is packaged with a large amount of chips attached to the wafer, the chip attached to the chip is decomposed by the heat of the package, and the thermally decomposed product destroys the package and becomes a cause of failure in the resulting device. Since the cutting chips are difficult to remove by washing, the yield of the cutting step is significantly reduced due to the occurrence of cutting chips. Therefore, when cutting with a rotating disc cutter, it is required to prevent the generation of cutting chips.

For the purpose of suppressing the occurrence of such cutting chips, Patent Document 1 discloses an invention that uses a polyolefin-based film irradiated with 1 to 80 Mrad of electron beams or gamma (gamma) rays as a base film for dicing sheets . In this invention, it is assumed that by irradiation of electron beams or gamma rays, crosslinks are formed by covalent linkages in the resin constituting the base film, and the generation of cutting chips is suppressed. [Prior Technical Literature] [Patent Literature]

Patent Document 1: Japanese Patent Application Laid-Open No. 5-211234

[The problem to be solved by the invention]

However, in the invention of Patent Document 1, due to the irradiation of radiation such as electron beams or gamma rays, as described above, once the resin is formed into a film shape, a manufacturing step is added, and the manufacturing cost is compared with general bases. The material film has a tendency to become taller.

The present invention was made in view of such circumstances, and its object is to provide an adhesive sheet capable of suppressing the production cost while further suppressing the generation of cutting chips. [Means to Solve the Problem]

In order to achieve the above object, first of all, the present invention is an adhesive sheet comprising a substrate and an adhesive layer on one side laminated on the substrate, characterized in that the substrate is made of polyester resin Among the monomer units constituting the polyester resin, the molar ratio of the monomer unit having an aromatic ring structure to the monomer unit having an alicyclic structure is 0 or more, which is less than 1 (Invention 1) .

In the adhesive sheet related to the above invention (Invention 1), since the base material is composed of a polyester resin-containing material, and in the polyester resin, monomer units having an alicyclic structure and monomer units having an aromatic ring structure The body unit has the above-mentioned molar ratio relationship, and even when it is used for cutting with a rotating disc cutter, the generation of cutting chips can still be suppressed well.

In the aforementioned invention (Invention 1), as the monomer unit constituting the polyester resin, the polyester resin preferably contains the dicarboxylic acid having the aforementioned alicyclic structure (Invention 2).

In the above inventions (Inventions 1 and 2), the polyester resin preferably contains a diol having the alicyclic structure as a monomer unit constituting the polyester resin (Invention 3).

In the above inventions (Inventions 1 to 3), the alicyclic structure and the number of carbon atoms constituting the ring are preferably 6 or more and 14 or less (Invention 4).

In the above inventions (Inventions 1 to 4), as the monomer unit constituting the polyester resin, the polyester resin contains a dimer acid obtained by dimerizing an unsaturated fatty acid, and the carbon number of the unsaturated fatty acid, It is preferably 10 or more, and 30 or less (Invention 5).

In the above invention (Invention 5), the ratio of the dimer acid as the monomer unit constituting the polyester resin with respect to the total dicarboxylic acid as the monomer unit constituting the polyester resin is 2 mol% Above, 25 mol% or less is preferable (Invention 6).

In the above inventions (Inventions 1 to 6), the tensile elastic modulus of the substrate at 23°C is preferably 100 MPa or more and 800 MPa or less (Invention 7).

In the above inventions (Inventions 1 to 7), the fracture ductility of the substrate at 23°C is preferably 200% or more and 800% or less (Invention 8).

In the above inventions (Inventions 1 to 8), the thickness of the substrate is preferably 20 μm or more and 600 μm or less (Invention 9).

In the above inventions (Inventions 1 to 9), the adhesive layer is preferably composed of an acrylic adhesive (Invention 10).

Among the above inventions (Inventions 1 to 10), it is preferable to use it as a sheet for processing a workpiece (Invention 11).

In the above invention (Invention 11), the above-mentioned workpiece processing sheet is preferably a dicing sheet (Invention 12). [Effects of the invention]

The adhesive sheet according to the present invention can be manufactured with reduced manufacturing costs, and the generation of cutting chips can be suppressed.

Hereinafter, an embodiment of the present invention will be described. The pressure-sensitive adhesive sheet according to this embodiment includes a substrate and an adhesive layer laminated on one side of the substrate. Although this adhesive sheet can be used in various applications like general adhesive sheets, it is particularly suitable as a workpiece processing sheet used for processing workpieces such as semiconductor wafers, and in particular, it is suitable for use in Cutting sheet used for cutting workpieces.

1. The composition of the adhesive sheet (1) Substrate The base material in this embodiment is made of a material containing polyester resin. Then, among the monomer units constituting the polyester resin, the molar ratio of the monomer unit having an aromatic ring structure to the monomer unit having an alicyclic structure is 0 or more and less than 1. Since the base material is composed of a material containing polyester resin exhibiting such a molar ratio, the adhesive sheet according to this embodiment is used when a rotating disc cutter is used to cut a workpiece, and it is possible to suppress chip formation well. occur.

The reason for obtaining such a chip suppression effect is presumed as follows. However, the possibility that the above-mentioned effects can be obtained by multiplying the following reasons with other reasons is not excluded, and the possibility that the above-mentioned effects can be obtained by reasons other than the following reasons is also not excluded.

First, it is presumed that when a cutting force is applied to a substrate made using this polyester resin, the polyester resin becomes easy to be cut at the position of the ester bond. Furthermore, the polyester resin in this embodiment has the above-mentioned mol ratio, and a part of the polymer chain has a structure (lamellar structure) with a moderately regular folding structure. Therefore, it is estimated that when a cutting force is applied, the polyester resin becomes easy to be cut at the position of the sheet structure. In this way, the polyester resin in the present embodiment is more likely to be cut at a specific position when receiving a cutting force than a resin used in a conventional base material.

Here, as a mechanism for generating chips from the base material of a general cut sheet, it is presumed that the base material is softened due to the frictional heat generated during cutting. In addition, the cutting of the base material is caused by contact with the rotating disc blade. Stretching force is applied to the broken part, and the cut part of the substrate is drawn off while being stretched. In particular, most of the cutting chips generated in this way have a filamentous form.

On the other hand, it is presumed that the substrate in this embodiment is effectively cut near the ester bond and the lamellar structure before being stretched as described above, and the generation of cutting chips is suppressed.

Such a cutting chip suppression effect can be exerted even if the substrate in this embodiment is not irradiated with radiation such as electron beams or gamma rays. Therefore, the adhesive sheet provided with this base material can reduce the manufacturing cost compared with the conventional dicing sheet manufactured by the method including the process of radiation irradiation.

In addition, the above-mentioned polyester resin is used as the base material of the material, and it is also easy to exhibit good flexibility. Therefore, the adhesive sheet according to the present embodiment has the effect of making it easy to stretch the adhesive sheet well (ductility) in the stretching step, and it becomes easy to push up from the backside of the wafer in the pick-up step, thereby This wafer can also obtain good effects such as easy picking up (pickup performance). Furthermore, since the above-mentioned polyester resin is used as the base material of the material, it has good transparency, and it becomes easy to visually recognize and inspect the workpiece through the adhesive sheet.

From the standpoint of easily achieving the aforementioned cutting chip suppression effect, among the monomer units constituting the polyester resin in this embodiment, the molar ratio of the monomer unit having an aromatic ring structure to the monomer unit having an alicyclic structure is Ratio is more preferably 0.5 or less, more preferably 0.2 or less, more preferably 0.1 or less, more preferably 0.05 or less, more preferably 0.03 or less, more preferably 0.01 or less, especially 0.005 or less Preferably, it is more preferably 0.001 or less, and 0 is the most preferable.

Furthermore, from the fact that the so-called molar ratio of "0" can be obtained, it is clear that the polyester resin in this embodiment may not contain a monomer unit having an aromatic ring structure.

(1-1) Polyester resin The specific composition of the polyester resin is not particularly limited as long as it satisfies the molar ratio.

From the viewpoint that it is easier to obtain a good chip suppression effect, the alicyclic structure possessed by the above-mentioned polyester resin preferably has 6 or more carbon atoms constituting the ring. In addition, the carbon number is preferably 14 or less, particularly preferably 10 or less. Especially, the above-mentioned carbon number is preferably 6. In addition, the alicyclic structure may be a monocyclic structure formed by one ring, a bicyclic structure formed by two rings, or one formed by three or more rings.

In addition, from the standpoint of easily obtaining a better chip suppression effect, as a monomer unit having the above-mentioned alicyclic structure, the above-mentioned polyester resin contains a dicarboxylic acid having an alicyclic structure and a dicarboxylic acid having an alicyclic structure. At least one of alcohols is preferred. In particular, from the viewpoint of easily obtaining a better chip suppression effect, the above-mentioned polyester resin preferably contains both of a dicarboxylic acid having an alicyclic structure and a diol having an alicyclic structure.

The structure of the above-mentioned dicarboxylic acid is not particularly limited as long as it has an alicyclic structure together with two carboxyl groups. For example, the dicarboxylic acid may have a structure in which two carboxyl groups are bonded to an alicyclic structure, or a structure in which an alkyl group or the like is further inserted between such an alicyclic structure and the carboxyl group. As preferred examples of such dicarboxylic acids, 1,2-cyclohexanedicarboxylic acid, 1,3-cyclohexanedicarboxylic acid, 1,4-cyclohexanedicarboxylic acid, 1,4 -Decahydronaphthalene dicarboxylic acid, 1,5-decahydronaphthalene dicarboxylic acid, 2,6-decahydronaphthalene dicarboxylic acid, 2,7-decahydronaphthalene dicarboxylic acid, etc., among these, 1, 5- 4-cyclohexanedicarboxylic acid is preferred. Such dicarboxylic acids may be derivatives such as alkyl esters. As such an alkyl ester derivative, for example, an alkyl ester having a carbon number of 1 or more and 10 or less may be used. As a more specific example, dimethyl ester, diethyl ester, etc. can be mentioned, and dimethyl ester is especially preferable.

When the polyester resin in this embodiment contains a dicarboxylic acid having an alicyclic structure as a monomer unit constituting it, the ratio of the dicarboxylic acid monomer to all monomer units constituting the polyester resin is It is preferably 20 mol% or more, more preferably 25 mol% or more, particularly preferably 30 mol% or more, and further preferably 35 mol% or more. In addition, the ratio is preferably 60 mol% or less, more preferably 55 mol% or less, particularly preferably 50 mol% or less, and further preferably 45 mol% or less. By being within these ranges, the adhesive sheet according to the present embodiment can easily achieve a better chip suppression effect.

In addition, when the polyester resin in this embodiment contains a dicarboxylic acid having an alicyclic structure as a monomer unit constituting it, it has an alicyclic ring relative to the entire dicarboxylic acid having a cyclic structure constituting the polyester resin. The ratio of the structured dicarboxylic acid is preferably 60% or more, more preferably 70% or more, particularly preferably 80% or more, and further preferably 90% or more. With the above ratio being 60% or more, the adhesive sheet according to this embodiment can easily achieve a better chip suppression effect. In addition, the upper limit of the ratio is not particularly limited, and for example, it may be 100% or less. Furthermore, among the above-mentioned dicarboxylic acids having a ring structure, in addition to the dicarboxylic acids having an alicyclic structure, dicarboxylic acids having an aromatic ring structure and the like are also included.

The structure of the above-mentioned diol is not particularly limited as long as it has an alicyclic structure together with two hydroxyl groups. For example, the diol may have a structure in which two hydroxyl groups are bonded to an alicyclic structure, or a structure in which an alkyl group is further inserted between such an alicyclic structure and a hydroxyl group. As preferred examples of such diols, 1,2-cyclohexanediol (especially 1,2-cyclohexanedimethanol), 1,3-cyclohexanediol (especially 1, 3-cyclohexanedimethanol), 1,4-cyclohexanediol (especially 1,4-cyclohexanedimethanol), 2,2-bis-(4-hydroxycyclohexyl)-propane, etc. Among others, 1,4-cyclohexanedimethanol is preferred.

When the polyester resin in this embodiment contains a diol having an alicyclic structure as the monomer unit constituting it, the ratio of the diol monomer to all monomer units constituting the polyester resin is 35 Mole% or more is preferable, particularly 40 mole% or more, and more preferably 45 mole% or more. In addition, the ratio is preferably 65 mol% or less, particularly preferably 60 mol% or less, and further preferably 55 mol% or less. By being within these ranges, the adhesive sheet according to the present embodiment can easily achieve a better chip suppression effect.

The polyester resin in this embodiment, from the viewpoint that the base material has the desired flexibility, the monomer unit constituting the polyester resin contains dimerization obtained by dimerizing an unsaturated fatty acid. Acid is better. Here, the carbon number of the unsaturated fatty acid is preferably 10 or more, especially 15 or more. In addition, the above-mentioned carbon number is preferably 30 or less, particularly preferably 25 or less. Examples of such dimer acids include dicarboxylic acids with 36 carbons, which are obtained by dimerizing unsaturated fatty acids with 18 carbons such as oleic acid and linoleic acid, and dicarboxylic acids with 36 carbons, such as erucic acid. Dicarboxylic acid with 44 carbon atoms can be obtained by dimerization of 22 unsaturated fatty acids. In addition, when the dimer acid is obtained, a small amount of trimer acid obtained by trimerizing the unsaturated fatty acid may also be produced in a small amount. The polyester resin in this embodiment contains the above-mentioned dimer acid, and may also contain such a trimer acid together.

When the polyester resin in this embodiment contains the above-mentioned dimer acid as the monomer unit constituting it, the ratio of the dimer acid relative to all the dicarboxylic acid units constituting the polyester resin is 2 mol% The above is preferable, especially 5 mol% or more is preferable, and 10 mol% or more is further preferable. In addition, the ratio is preferably 25 mol% or less, particularly preferably 23 mol% or less, and further preferably 20 mol% or less. By being in these ranges, the polyester resin tends to have the desired flexibility, and as a result, the adhesive sheet according to this embodiment can achieve excellent ductility and pick-up properties.

Examples of monomer units having the above aromatic ring structure include phthalic acid, terephthalic acid, isophthalic acid, 2,6-naphthalenedicarboxylic acid, 1,4-naphthalenedicarboxylic acid, 4,4 Aromatic dicarboxylic acids such as'-biphthalic acid.

The polyester resin in this embodiment may contain monomers other than the above-mentioned dicarboxylic acid, diol, and dimer acid as a monomer unit constituting it. Examples of such monomers include aliphatic dicarboxylic acids such as succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, and sebacic acid. In addition, diol components other than the diol having an alicyclic structure may be contained. For example, ethylene glycol, propylene glycol, butylene glycol, hexanediol, octanediol, decanediol; ethylene oxide adducts such as bisphenol A and bisphenol S; trimethylolpropane and the like may also be contained.

In addition, for the polyester resin in this embodiment, the heat of fusion measured at a heating rate of 20°C/min by differential scanning calorimetry is preferably 2J/g or more, more preferably 5J/g or more, especially It is preferably 10 J/g or more, and more preferably 15 J/g or more. When the heat of fusion is 2 J/g or more, it becomes easier to achieve the chip suppression effect. On the other hand, the upper limit of the heat of fusion is not particularly limited. For example, it may be 150 J/g or less, or 100 J/g or less, especially 70 J/g or less, and further 50 J/g or less, especially It can be 30J/g or less. In addition, the details of the method for measuring the heat of fusion described above are as described in the column of the following Examples.

The manufacturing method of the polyester resin in this embodiment is not particularly limited, and a conventional catalyst can be used to polymerize the above-mentioned monomer components to obtain a polyester resin.

The ratio of the polyester resin relative to all the components constituting the substrate in this embodiment is preferably 50% or more, particularly 60% or more, and more preferably 70% or more. With the above-mentioned ratio being 50% or more, the adhesive sheet according to this embodiment is easier to achieve an excellent chip suppression effect. In addition, the upper limit of the above-mentioned ratio is not particularly limited. For example, it may be 100% or less.

(1-2) Other ingredients The material used to manufacture the base material in this embodiment may contain other components other than the above-mentioned polyester resin. In particular, the material may also contain components that can be used in the base material of a general adhesive sheet (especially the base material of a sheet for general work processing).

Examples of such components include various additives such as flame retardants, plasticizers, lubricants, antioxidants, colorants, infrared absorbers, ultraviolet absorbers, and ion scavengers. Although there is no particular limitation on the content of such additives, it is preferably a range in which a desired function is exerted on the substrate.

(1-3) The composition of the base material As the layer structure of the substrate in this embodiment, as long as it has a layer (hereinafter, sometimes referred to as a "polyester resin layer") composed of a material containing the above-mentioned polyester resin, it may be a single layer or a plurality of layers. Floor. From the viewpoint of reducing the manufacturing cost, the substrate in this embodiment is preferably a single layer (only a polyester resin layer).

On the other hand, in the case of plural layers, plural polyester resin layers may be laminated, or the polyester resin layer and other layers may be laminated. In the latter case, in the layer structure of the base material, a polyester resin layer is preferably a layer formed by laminating the adhesive layer. At this time, it becomes possible to have both the cutting chip suppression effect by the polyester resin layer and the desired effect by other layers.

In addition, in order to improve the adhesion to the adhesive layer on the surface of the substrate on which the adhesive layer is laminated, surface treatments such as primer treatment, corona treatment, and plasma treatment may be performed.

(1-4) Preparation method of base material The manufacturing method of the base material in this embodiment is not particularly limited as long as it uses a polyester resin-containing material. For example, melt extrusion methods such as the T-die method and the round die method; calendering method; dry method and wet method can be used. Formula method, etc., solution method, etc. Among these, from the viewpoint of efficiently manufacturing the base material, it is preferable to use a melt extrusion method or a calender method.

When the base material formed of a single layer is manufactured by the melt extrusion method, the material of the base material (material containing the above-mentioned polyester resin) is kneaded, and the kneaded material obtained is directly or temporarily manufactured into pellets, and then used A conventional extruder can be used to form a film.

In addition, when a base material formed of a plurality of layers is produced by a melt extrusion method, the components constituting each layer are kneaded separately, and the obtained kneaded material is directly or temporarily manufactured into pellets, and then a conventional extrusion method is used. Out of the machine, multiple layers can be extruded at the same time to make a film.

(1-5) Physical properties of the substrate, etc. The coefficient of tensile elasticity of the substrate in this embodiment at 23°C is preferably 800 MPa or less, particularly preferably 600 MPa or less, and further preferably 500 MPa or less. In addition, the aforementioned coefficient of tensile elasticity is preferably 100 MPa or more, especially 200 MPa or more, and more preferably 300 MPa or more. With the above-mentioned tensile elasticity coefficient of 800 MPa or less, the base material in the present embodiment becomes easy to have the desired flexibility, and the adhesive sheet according to the present embodiment also becomes easy to realize excellent ductility and pick-up properties. In addition, with the above-mentioned tensile elastic coefficient of 100 MPa or more, the base material in this embodiment is easy to have moderate strength, and the adhesive sheet has good operability, and at the same time, it becomes easy to perform the desired workpiece processing well. . In addition, the details of the method for measuring the above-mentioned tensile modulus of elasticity are as described in the following test examples.

The breaking point stress of the substrate in this embodiment at 23°C is preferably 60 MPa or less, particularly preferably 50 MPa or less, and further preferably 40 MPa or less. In addition, the above-mentioned breaking point stress is preferably 15 MPa or more, especially 20 MPa or more, and further preferably 25 MPa or more. When the stress at the breaking point is 60 MPa or less, the base film according to this embodiment has better workability. In addition, since the breaking point stress is 15 MPa or more, the base material in the present embodiment is easy to have moderate strength, the adhesive sheet has good operability, and it becomes easy to perform desired workpiece processing well. Furthermore, since the stress at the breaking point is 15 MPa or more, the base film according to this embodiment has good ductility. In addition, the details of the method for measuring the stress at the breaking point are as described in the following test examples.

The fracture ductility of the substrate in this embodiment at 23°C is preferably 200% or more, more preferably 250% or more, particularly preferably 300% or more, and more preferably 350% or more. When the fracture ductility is 200% or more, the base material in this embodiment can easily have the desired extensibility, and the adhesive sheet according to this embodiment can easily achieve excellent ductility and pick-up properties. In addition, the above-mentioned fracture ductility is preferably 800% or less, more preferably 700% or less, particularly preferably 600% or less, and further preferably 500% or less. When the fracture ductility is 800% or less, the workability of the base material becomes better, and it becomes easier to manufacture the desired sheet for workpiece processing. In addition, the details of the method for measuring the fracture ductility described above are as described in the following test examples.

The thickness of the substrate in this embodiment is preferably 20 μm or more, particularly preferably 40 μm or more, and more preferably 60 μm or more. In addition, the thickness of the substrate is preferably 600 μm or less, particularly preferably 300 μm or less, and more preferably 200 μm or less. When the thickness of the substrate is 20 μm or more, the adhesive sheet becomes easy to have moderate strength, and it becomes easy to well support the workpiece fixed on the adhesive sheet. As a result, the occurrence of chipping during cutting can be effectively suppressed. In addition, when the thickness of the substrate is 600 μm or less, it becomes easy to achieve the fracture ductility described above. Furthermore, when the thickness of the base film is 600 μm or less, the base film has better workability.

(2) Adhesive layer As the adhesive constituting the adhesive layer in this embodiment, there is nothing special as long as it can exert sufficient adhesion to the adherend (especially for processing the workpiece, and the adhesion to the workpiece becomes sufficient). limited. Examples of adhesives constituting the adhesive layer include acrylic adhesives, rubber-based adhesives, silicone-based adhesives, urethane-based adhesives, polyester-based adhesives, and polyvinyl ether-based adhesives. Among these, it is preferable to use an acrylic adhesive from the viewpoint of easily exhibiting the desired adhesive force.

The adhesive constituting the adhesive layer in this embodiment may be an adhesive that does not have active energy ray curability. However, an adhesive having active energy ray curability (hereinafter, sometimes referred to as "active energy ray Hardening adhesive") is preferred. Since the adhesive layer is composed of an active energy ray curable adhesive, the active energy ray is irradiated to harden the adhesive layer, which can easily reduce the adhesive force of the adhesive sheet to the adherend. In particular, when the pressure-sensitive adhesive sheet according to the present embodiment is used as a sheet for processing a workpiece, the processed workpiece can be easily separated from the pressure-sensitive adhesive sheet by irradiation of active energy rays.

The active energy ray curable adhesive constituting the adhesive layer may be a polymer with active energy ray curability as the main component, or it may be an active energy ray non-curing polymer (without active energy ray Curable polymer), and a mixture of monomers and/or oligomers having at least one active energy ray curable group as the main component.

A polymer having active energy ray curability is a (meth)acrylate polymer (hereinafter, sometimes referred to as " Active energy ray curable polymer") is preferred. This active energy ray curable polymer is preferably obtained by reacting an acrylic copolymer having a functional group-containing monomer unit with an unsaturated group-containing compound having a functional group bonded to the functional group. In addition, in this specification, (meth)acrylic acid means both acrylic acid and methacrylic acid. Other similar terms are also the same. Furthermore, the term "polymer" also includes the concept of "copolymer".

The weight average molecular weight of the active energy ray-curable polymer is preferably 10,000 or more, particularly preferably 150,000 or more, and further preferably 200,000 or more. In addition, the weight average molecular weight is preferably 2.5 million or less, particularly preferably 2 million or less, and further preferably 1.5 million or less. In addition, the weight average molecular weight (Mw) in this specification is a value measured by gel permeation chromatography (GPC method) in terms of standard polystyrene conversion.

On the other hand, when the active energy ray curable adhesive is a mixture of the active energy ray non-curable polymer component and a monomer and/or oligomer having at least one active energy ray curable group In the case of the main component, as the active energy ray non-curable polymer component, for example, the above-mentioned acrylic copolymer before reacting the unsaturated group-containing compound can be used. In addition, as active energy ray-curable monomers and/or oligomers, for example, esters of polyhydric alcohol and (meth)acrylic acid can be used.

The weight average molecular weight of the acrylic polymer as the active energy ray non-curable polymer component is preferably 10,000 or more, particularly preferably 150,000 or more, and more preferably 200,000 or more. In addition, the weight average molecular weight is preferably 2.5 million or less, particularly preferably 2 million or more, and further preferably 1.5 million or less.

In addition, when ultraviolet rays are used as the active energy ray for curing the active energy ray curable adhesive, it is preferable to add a photopolymerization initiator to the adhesive. In addition, to this adhesive, an active energy ray non-curable polymer component or an oligomer component, a crosslinking agent, etc. may be added.

The thickness of the adhesive layer in this embodiment is preferably 1 μm or more, particularly 2 μm or more, and more preferably 3 μm or more. In addition, the thickness of the adhesive layer is preferably 50 μm or less, particularly preferably 40 μm or less, and further preferably 30 μm or less. When the thickness of the adhesive layer is 1 μm or more, the adhesive sheet according to this embodiment can easily exhibit the desired adhesiveness. In addition, since the thickness of the adhesive layer is 50 μm or less, when the cured adhesive layer is separated from the adherend, it is easy to separate.

(3) Peel the sheet The adhesive sheet according to this embodiment aims to protect the surface of the adhesive layer on the opposite side of the substrate (hereinafter, sometimes referred to as "adhesive surface") to the adherend. , You can also peel off the sheet in this area layer.

The configuration of the above-mentioned release sheet is arbitrary, and for example, a plastic film is subjected to a release treatment with a release agent or the like. Specific examples of the plastic film include polyester films such as polyethylene terephthalate, polybutylene terephthalate, and polyethylene naphthalate; and polypropylene, polyethylene, etc. Of polyolefin film. As the above-mentioned release agent, silicone-based, fluorine-based, long-chain alkane-based, etc. can be used. Among these, silicone-based products that are inexpensive and have stable performance are preferred.

The thickness of the release sheet is not particularly limited, and for example, it may be 20 μm or more and 250 μm or less.

(4) Other In the adhesive sheet according to this embodiment, an adhesive layer may be laminated on the surface of the adhesive layer on the side opposite to the base material. In this case, the adhesive sheet related to this embodiment can be used as a dicing-die bonding sheet. The sheet is attached to the work piece on the surface of the adhesive layer opposite to the adhesive layer, and by cutting the work piece together with the adhesive layer, a wafer with laminated adhesive layers can be obtained. The chip can be easily fixed to the object on which the chip is mounted through the adhesive layer formed into pieces. As the material constituting the above-mentioned adhesive layer, a thermosetting adhesive component containing a thermoplastic resin and a low molecular weight, a thermosetting adhesive component containing a B-stage (semi-cured form), and the like are preferably used.

In addition, in the adhesive sheet related to this embodiment, a protective film forming layer may be laminated on the adhesive surface of the adhesive layer. In this case, the adhesive sheet according to this embodiment can be used as a sheet for forming a protective film and dicing. For this type of sheet, the workpiece is attached to the surface of the protective film forming layer on the opposite side of the adhesive layer, and by cutting the workpiece together with the protective film forming layer, a laminated protective film forming layer can be obtained. Wafer. As the workpiece, it is preferable to use one having a circuit formed on one side. In this case, usually, a protective film forming layer is laminated on the surface opposite to the surface on which the circuit is formed. The protective film forming layer formed into pieces can be cured at a specific time to form a protective film with sufficient durability on the wafer. The protective film forming layer is preferably formed of an uncured curable adhesive.

2. Manufacturing method of adhesive sheet The manufacturing method of the adhesive sheet concerning this embodiment is not specifically limited. For example, after an adhesive layer is formed on a release sheet, one side of the base material is laminated on the side of the adhesive layer opposite to the release sheet to obtain an adhesive sheet.

The formation of the above-mentioned adhesive layer can be performed by a conventional method. For example, a coating liquid containing an adhesive composition for forming an adhesive layer and, if necessary, further containing a solvent or a dispersion medium is prepared. Then, the above-mentioned coating liquid is applied to the releasable surface of the release sheet (hereinafter, sometimes referred to as "release surface"). Next, by drying the obtained coating film, an adhesive layer can be formed.

The coating of the above-mentioned coating liquid can be carried out by a conventional method, for example, a rod coating method, a knife coating method, a roll coating method, a flap coating method, a die coating method, or a gravure coating method can be used. Bufa and so on. In addition, the coating liquid is not particularly limited as long as it can be applied, and it may contain components for forming the adhesive layer as a solute, or may contain it as a dispersant. In addition, the release sheet can also be peeled off as a process material, and can also protect the adhesive layer during the time it is attached to the adherend.

When the adhesive composition used to form the adhesive layer contains the above-mentioned crosslinking agent, by changing the above-mentioned drying conditions (temperature, time, etc.), or by additionally setting heat treatment, the polymer composition in the coating film The crosslinking reaction with the crosslinking agent is carried out, and the crosslinking structure is preferably formed in the adhesive layer at a desired density. Furthermore, in order to fully advance the above-mentioned crosslinking reaction, after bonding the adhesive layer and the base material, for example, aging may be performed such as standing for several days in an environment of 23° C. and a relative humidity of 50%.

3. How to use the adhesive sheet Although the adhesive sheet according to this embodiment can be used for various applications similar to general adhesive sheets, it is particularly suitable for use as a workpiece processing sheet used in the processing of workpieces such as semiconductor wafers. In this case, after the adhesive surface of the adhesive sheet according to this embodiment is attached to the workpiece, the workpiece can be processed on the adhesive sheet. In response to processing, the adhesive sheet related to this embodiment can be used as a sheet for workpiece processing such as a back grinding sheet, a dicing sheet, an expanded sheet, and a wafer picking sheet. Here, as an example of a workpiece, a semiconductor member such as a semiconductor wafer and a semiconductor package, and a glass member such as a glass plate can be cited.

The adhesive sheet according to the present embodiment, as described above, when used for cutting with a rotating disc cutter, the generation of cutting chips can be suppressed satisfactorily. Therefore, the adhesive sheet according to this embodiment is particularly suitable for use as a dicing sheet among the above-mentioned workpiece processing sheets.

In addition, when the adhesive sheet according to this embodiment includes the above-mentioned adhesive layer, the adhesive sheet can be used as a dicing-die bonding sheet. In addition, when the pressure-sensitive adhesive sheet according to this embodiment includes the protective film forming layer described above, the pressure-sensitive adhesive sheet can be used as a protective film forming and dicing sheet.

In addition, when the adhesive layer in the adhesive sheet according to this embodiment is composed of the active energy ray-curable adhesive, it is better to irradiate it with subsequent active energy rays during use. In other words, when the workpiece is processed on the adhesive sheet and the processed workpiece is separated from the adhesive sheet, it is better to irradiate the adhesive layer with active energy rays before the separation. As a result, the adhesive layer is hardened, the adhesive force of the adhesive sheet to the processed workpiece is significantly reduced, and the separation of the processed workpiece becomes easy.

The embodiments described above are described in order to facilitate the understanding of the present invention, and are not described to limit the present invention. Therefore, the gist of each element disclosed in the above embodiment includes all design changes and equivalents within the scope of the technology of the present invention. [Example]

Hereinafter, although the present invention will be described in further detail with examples and the like, the scope of the present invention is not limited to these examples and the like.

[Example 1] (1) Preparation of substrate In a reactor equipped with a stirrer, a distillation tube, and a decompression device, pour 12.90 kg of dimethyl 1,4-cyclohexanedicarboxylate (98% trans-body ratio) and 1,4-cyclohexanedimethanol 11.47 kg, 0.3 kg of ethylene glycol, and 0.11 kg of an ethylene glycol solution containing 10% manganese acetate tetrahydrate were heated to 200°C under a nitrogen stream, and then the temperature was raised to 230°C in 1 hour. This is maintained for 2 hours, after transesterification reaction, 10.30 kg of erucic acid-derived dimer acid (carbon number 44, manufactured by Croda, product name "PRIPOL1004"), ethylene glycol containing 10% trimethyl phosphate 0.11 kg of the solution was put into the reaction system, and then the esterification reaction was carried out at 230°C for 1 hour. Next, after adding 300 ppm of germanium dioxide as a polycondensation catalyst with stirring, the pressure was reduced to 133 Pa or less in 1 hour. During this time, the internal temperature was increased from 230°C to 270°C, and the mixture was stirred under a high vacuum of 133 Pa or less until it reached a specific level. Viscosity, undergoes polycondensation reaction. The obtained polymer is extruded in water into strips, cut into pellets.

The pellets of the polyester resin thus obtained were dried at 85°C for 4 hours or more, and then put into the hopper of the single-screw extruder provided with the T die. Then, the above resin was extruded from the T die in a melt-kneaded state under the conditions of a drum temperature of 220°C and a mold temperature of 220°C, and was cooled by a cooling roll to obtain a sheet-like substrate with a thickness of 80 μm. .

And, as a monomer constituting the resin, the above-mentioned polyester resin contains about 50 mol% of 1,4-cyclohexanedimethanol and about 40.5 mol% of dimethyl 1,4-cyclohexanedicarboxylate. And 9.5 mol% of dimer acid derived from erucic acid. In other words, among the monomer units constituting the polyester resin, the molar ratio of the monomer unit having an aromatic ring structure to the monomer unit having an alicyclic structure is 0. In addition, the ratio of the dimer acid to all the dicarboxylic acid units constituting the polyester resin was 19.1 mol%. In addition, the heat of fusion of the above-mentioned polyester resin, measured by the following method, was 20 J/g.

(2) Preparation of adhesive composition 95 parts by mass of n-butyl acrylate and 5 parts by mass of acrylic acid were polymerized by a solution polymerization method to obtain a (meth)acrylate polymer. The weight average molecular weight (Mw) of this acrylic polymer, measured by the following method, was 500,000.

Mix 100 parts by mass of the (meth)acrylate polymer obtained as described above (in terms of solid content, the same below), 120 parts by mass of urethane acrylate oligomer (Mw: 8,000), and isocyanate-based crosslinking agent (Manufactured by Tosoh Co., Ltd., product name "Coronate L") 5 parts by mass, and 4 parts by mass photopolymerization initiator (manufactured by IGM Resins B.V., product name "Omnirad 184") to obtain an energy ray hardening type Adhesive composition.

(3) Formation of adhesive layer The adhesive composition obtained in the above step (2) is coated on one side of a polyethylene terephthalate film with a thickness of 38μm. It is a release sheet (LINTEC Co., Ltd., product name "SP-PET381031"), and the resulting coating film was dried at 100°C for 1 minute. In this way, a laminate in which an adhesive layer having a thickness of 10 μm was formed on the release surface of the release sheet was obtained.

(4) Production of adhesive sheet The sheet surface of the substrate obtained in the above step (1) is bonded to the surface on the adhesive layer side of the laminate obtained in the above step (3) to obtain an adhesive sheet.

Here, the heat of fusion of the polyester resin is measured using a differential scanning calorimeter (DSC, manufactured by TA Instruments, product name "DSC Q2000") based on JIS K 7121:2012.

Specifically, first, heating is performed from room temperature to 250°C at a temperature increase rate of 20°C/min, maintained at 250°C for 10 minutes, and reduced to -60°C at a temperature decrease rate of 20°C/min, and maintained at -60°C for 10 minutes. After that, it was heated again to 250°C at a heating rate of 20°C/min to obtain a DSC curve and measure the melting point.

In addition, the above-mentioned weight average molecular weight (Mw) is the weight average molecular weight of standard polystyrene in terms of conversion measured (GPC measurement) using a gel permeation chromatography (GPC) under the following conditions. <Measurement conditions> . Measuring device: manufactured by Tosoh Corporation, HLC-8320 . GPC string (passed in the following order): manufactured by Tosoh Co., Ltd. TSK gel superH-H TSK gel superHM-H TSK gel superH2000 . Determination solvent: tetrahydrofuran . Measuring temperature: 40°C.

[Comparative Example 1] An adhesive sheet was obtained in the same manner as in Example 1, except that a polyvinyl chloride resin sheet having a thickness of 80 μm was used as the base material. In addition, the heat of fusion of the above-mentioned polyvinyl chloride resin, measured by the above-mentioned method, was 0 J/g.

[Comparative Example 2] In addition to using ethylene-methacrylic acid copolymer (EMAA), a substrate (thickness 80μm) treated with electron beam irradiation on one side as the substrate, and the electron beam irradiation surface of the substrate is laminated Except for the adhesive layer, an adhesive sheet was obtained in the same manner as in Example 1. In addition, the heat of fusion of the ethylene-methacrylic acid copolymer, measured by the method described above, was 81 J/g.

[Comparative Example 3] Except for the use of a substrate (80μm thick) made of EMAA with electron beam irradiation treatment on one side as the substrate, and the electron beam irradiation surface of the substrate is laminated with an adhesive layer, the rest are the same as the examples 1 In the same way, an adhesive sheet was obtained. In addition, the electron beam irradiation dose of the substrate used in Comparative Example 3 was twice the electron beam irradiation dose of the substrate used in Comparative Example 2. In addition, the heat of fusion of the ethylene-methacrylic acid copolymer, measured by the method described above, was 79 J/g.

[Comparative Example 4] The adhesion was obtained in the same manner as in Example 1, except that a resin sheet with a thickness of 80 μm produced by using a glycol-modified polyester resin having a structure represented by the following general formula (1) was used as a base material. piece. And, from the structure of the following general formula (1), it can be seen that among the monomer units constituting the glycol-modified polyester resin, the molar ratio of the monomer unit having an aromatic ring structure is relative to the monomer unit having an alicyclic structure. Than more than 1. In addition, the heat of fusion of the diol-modified polyester resin, measured by the method described above, was 0 J/g. [化1]

[Comparative Example 5] An adhesive sheet was obtained in the same manner as in Example 1, except that a resin sheet having a thickness of 80 μm produced using an amorphous polyester resin having a structure represented by the following general formula (2) was used as a base material. And, as can be seen from the structure of the following general formula (2), among the monomer units constituting the amorphous polyester resin, the molar ratio of the monomer unit having an aromatic ring structure relative to the monomer unit having an alicyclic structure The ratio is 1. In addition, the heat of fusion of the above-mentioned amorphous polyester resin, measured by the above-mentioned method, was 0 J/g. [化2]

[Test Example 1] (Measurement of the tensile properties of the base material) The substrates produced in the examples and comparative examples were cut into test pieces of 15 mm×150 mm. At this time, the side of 150 mm is parallel to the MD direction of the substrate (the flow direction during substrate manufacturing), and the side of 15 mm is parallel to the TD direction of the substrate film (the direction perpendicular to the above MD direction). , To cut. Then, regarding this test piece, the tensile elastic modulus, fracture ductility, and fracture point stress were measured in accordance with JIS K7127: 1999.

Specifically, the above-mentioned test piece was set to a distance of 100 mm between the chucks in a tensile testing machine (manufactured by Shimadzu Corporation, product name "AUTOGRAPH AG-Xplus 100N"), and then set at a speed of 200 mm/min under an environment of 23°C. , A tensile test was performed on the MD direction of the base film to determine the tensile elastic modulus (MPa), fracture ductility (%), and fracture point stress (MPa). The results are shown in Table 1.

[Test Example 2] (Measurement of the number of chips) The release sheet was peeled off from the adhesive sheets manufactured in the Examples and Comparative Examples, and the exposed surface of the exposed adhesive layer was attached to a single side of a silicon wafer with a thickness of 40 μm, and then the edge of the exposed surface in the adhesive sheet Part (a position that does not overlap with the silicon wafer) is attached to the ring frame for dicing. Next, using a dicing machine (manufactured by Disco Corporation, product name "DFD6362"), the silicon wafer was diced under the following conditions. . Workpiece (attachment): silicon wafer . Workpiece size: diameter 6 inches, thickness 40μm . Cutting blade: manufactured by Disco Corporation, product name "27HECC", diamond blade . Rotation of the blade: 50,000rpm . Cutting speed: 100mm/sec . Cutting depth: starting from the surface of the substrate, cutting to a depth of 20μm . Cutting size: 8mm×8mm.

After dicing, the silicon wafer is sliced into pieces and the wafer is attached to the adhesive sheet as it is. The amount of cutting chips generated on the saw path (the cutting path generated by the cutting edge) is measured using an electron microscope ( Manufactured by Keyence Corporation, product name "VHX-5000", magnification: 500 times) count. At this time, the saw roads exist in a plurality of saw roads in the vertical direction and the horizontal direction, respectively, and the number of cutting chips present on the three paths near the center in the vertical direction and the three paths near the center in the horizontal direction are counted. The counting results are shown in Table 1.

[Table 1] Substrate Stretching properties of the substrate Number of cutting chips (a) Resin Electron beam irradiation Tensile coefficient of elasticity (MPa) Fracture ductility (%) Stress at rupture point (MPa) type Mole ratio (monomers with aromatic ring structure/monomers with alicyclic structure) Heat of fusion (J/g) Example 1 polyester resin 0 20 none 400 390 32 72 Comparative example 1 Polyvinyl chloride resin - 0 none 328 290 28 202 Comparative example 2 Ethylene-methacrylic acid copolymer - 81 have 115 353 26 272 Comparative example 3 Ethylene-methacrylic acid copolymer - 79 Yes (2 times of Comparative Example 2) 138 223 26 188 Comparative example 4 Glycol modified polyester resin More than 1 0 none 1570 380 59 241 Comparative example 5 Amorphous polyester resin 1 0 none 1465 280 69 153

It can be clearly seen from Table 1 that the adhesive sheets manufactured in the examples can effectively suppress the generation of chips during cutting. [Industry Availability]

The pressure-sensitive adhesive sheet of the present invention is suitable for use as a workpiece processing sheet used for processing workpieces such as semiconductor wafers.

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Claims (12)

An adhesive sheet is an adhesive sheet provided with a base material and an adhesive layer laminated on one side of the base material, and is characterized in that: The above-mentioned substrate is composed of a material containing polyester resin, Among the monomer units constituting the polyester resin, the molar ratio of the monomer unit having an aromatic ring structure to the monomer unit having an alicyclic structure is 0 or more and less than 1. The adhesive sheet according to claim 1, wherein the polyester resin contains a dicarboxylic acid having the alicyclic structure as a monomer unit constituting the polyester resin. The adhesive sheet according to claim 1, wherein the polyester resin contains a diol having the alicyclic structure as a monomer unit constituting the polyester resin. The adhesive sheet of claim 1, wherein the alicyclic structure described above has a carbon number of 6 or more and 14 or less. The adhesive sheet of claim 1, wherein, as a monomer unit constituting the polyester resin, the polyester resin contains a dimer acid obtained by dimerizing an unsaturated fatty acid, The carbon number of the above-mentioned unsaturated fatty acid is 10 or more and 30 or less. The adhesive sheet of claim 5, wherein the ratio of the dimer acid as the monomer unit constituting the polyester resin is 2 mol% relative to the total dicarboxylic acid as the monomer unit constituting the polyester resin Above, 25 mol% or less. The adhesive sheet of claim 1, wherein the tensile elastic modulus of the substrate at 23° C. is 100 MPa or more and 800 MPa or less. The adhesive sheet of claim 1, wherein the fracture ductility of the above-mentioned substrate at 23°C is 200% or more and 800% or less. The adhesive sheet of claim 1, wherein the thickness of the substrate is 20 μm or more and 600 μm or less. The adhesive sheet of claim 1, wherein the adhesive layer is composed of an acrylic adhesive. Such as the adhesive sheet of claim 1, which is used as a sheet for workpiece processing. Such as the adhesive sheet of claim 11, wherein the above-mentioned workpiece processing sheet is a cut sheet.